SharePoint 2013: drag files here disabled

Problem

You are remoted into a farm server.  You connect to a SharePoint 2013 website while in this remote session, and then navigate to a document folder.  You then attempt to drag a file onto the folder, but the drag files here option seems disabled.

Solution

1. Verify that the Desktop Experience feature has been setup on the server [1,2].
2. If it is already, then check the browser type and version you are using on the server [3].

References

1. Enable Desktop Experience on Servers to Access SharePoint Web Folders
2. Desktop Experience Overview
3. SharePoint Server 2013: Drag and drop contents to Library